A high-hardness, high-wear-resistant coating for rotary tillers and its preparation method

Abstract

The application provides a high-hardness and high-wear-resistance coating on a rotary tiller blade surface and a preparation method. A mixed powder of iron-based powder Fe60 and WC powder is uniformly mixed with a binder, and then is applied on the surface of the rotary tiller blade to prepare a composite melting coating through laser cladding. The coating has the advantages of high hardness, high wear resistance and high bonding strength, and the surface hardness is greater than 1400HV, so that the hardness and wear resistance of the rotary tiller blade are greatly improved, the effective service life of the blade is prolonged, and the production cost is reduced. The preparation method is simple and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of agricultural rotary tillage machinery and equipment technology, specifically to a high-hardness wear-resistant coating on the surface of rotary tillage blades and its preparation method. Background Technology

[0002] my country is a major agricultural country, with dryland accounting for over 50% of its total arable land, according to statistics. Agricultural mechanization is a key characteristic of my country's modern agriculture. In 2020, the overall level of mechanized farming in my country reached 70%. Rotary tillers, due to their excellent soil-breaking performance, strong adaptability, and high efficiency, hold an important position among tillage machinery and are widely used.

[0003] However, the key soil-contact component of domestic agricultural machinery—the rotary tiller blade—is prone to wear, has a short lifespan, and a high failure rate, which has been a persistent problem for farmers. The rotary tiller blades operate in extremely harsh environments, enduring frequent impacts, scrapes, and friction from soil sand, gravel, crop stalks, and weeds during use, making them highly susceptible to wear and failure (see...). Figure 1 According to statistics, even in plain areas, most rotary tillage operations cover 30 hectares. 2 -40 hm 2 Afterwards, they will become unusable due to wear. Because of the poor wear resistance of the blades, the average trouble-free working time of domestically produced rotary tillers and combine harvesters is only 1 / 3 to 1 / 2 of that of similar foreign products. On the other hand, the average pass rate of rotary tiller blades in spot checks is also very low, at 58.3%, which seriously affects their tillage effect and service life. The easy wear of rotary tiller blades severely affects the working quality of the rotary tiller, thus further affecting crop growth. Failures caused by wear often require multiple blade replacements for the same rotary tiller within a single working season. Frequent blade replacements not only increase operating costs and the labor intensity of users, but also affect operating efficiency and even delay farming seasons. In addition, due to wear, the rotary tiller blades become narrower and blunter, affecting operating effect and efficiency while increasing traction resistance and tractor fuel consumption. Therefore, developing new wear-resistant strengthening processes for rotary tiller blades is of great significance for improving the wear resistance of rotary tiller blades, extending their service life, and reducing losses caused by wear. It is also of great significance for improving the quality and level of key equipment parts for rotary tiller agricultural machinery in my country.

[0004] As mentioned earlier, the main failure mode of rotary tillers is wear, and improving their wear resistance is currently the main research direction. With the steel substrate material remaining unchanged, surface modification of the steel substrate is an effective method to improve wear resistance. Hardness is an important indicator for improving wear resistance. This invention improves wear resistance and reduces wear during operation by preparing a high-hardness wear-resistant coating on the surface of the rotary tiller. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a high-hardness, high-wear-resistant coating for the surface of rotary tillers and its preparation method. This invention directly prepares the coating on the base steel of the finished rotary tiller. The coating has advantages such as high hardness, high wear resistance, and high bonding strength, and the preparation method is simple. It can significantly improve the hardness and wear resistance of the rotary tiller, extend the effective service life of the tool, and thus reduce production costs, making it suitable for widespread application.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] A method for preparing a high-hardness, high-wear-resistant coating on the surface of a rotary tiller blade, characterized by comprising the following steps:

[0008] (1) Clean the surface of the rotary tiller blades and dry them;

[0009] (2) After mechanically mixing the iron-based powder Fe60 and WC powder, add the binder and mix well. Apply the mixture to the surface of the rotary tiller blade and flatten it.

[0010] (3) Laser cladding is performed on the rotary tiller blade workpiece after powdering. The laser power is 1200W, the scanning speed is 7mm / s, and the overlap rate is 50%.

[0011] Furthermore, the mass ratio of the iron-based powder Fe60 to the WC powder is 7-6:3-4.

[0012] Furthermore, the thickness of the powder in step (2) is 1.5 mm.

[0013] Furthermore, in step (2), the adhesive used is a 5% polyvinyl alcohol solution by volume.

[0014] Furthermore, the particle size of the WC powder is 100-150 μm, and the particle size of the iron-based powder Fe60 is 100-200 μm.

[0015] The rotary tiller blade prepared by the aforementioned method has a high-hardness and high-wear-resistant coating on its surface.

[0016] The high-hardness, high-wear-resistant coating on the surface of the rotary tiller blade is characterized in that the microhardness of the coating is greater than 1400 HV.

[0017] The present invention discloses a method for preparing a high-hardness, high-wear-resistant coating on the surface of a rotary tiller blade. A mixture of iron-based powder (Fe60) and WC powder is mixed with a binder and then applied to the surface of the rotary tiller blade. A composite fused coating is then prepared by laser cladding. This coating exhibits advantages such as high hardness, high wear resistance, and high bonding strength, with a surface hardness greater than 1400 HV. This significantly improves the hardness and wear resistance of the rotary tiller blade, extends its effective service life, and thus reduces production costs. The preparation method is simple and easy to operate. Attached Figure Description

[0018] Figure 1 This is a diagram showing the rotary tiller blades and their wear condition.

[0019] Figure 2 The images show the rotary tiller blade, the cut sample, and the cleaned sample.

[0020] Figure 3 (a) and (b) are microscopic morphology diagrams of WC powder and Fe60 iron-based powder used in this invention, respectively.

[0021] Figure 4 (a) is a physical image of the coating prepared in Example 1, and (b) and (c) are cross-sectional microscopic images.

[0022] Figure 5 (a), (b), and (c) are microstructure distribution diagrams of the bottom, middle, and top sections of the coating prepared in Example 1.

[0023] Figure 6 (a) and (b) are XRD phase analysis diagrams of the rotary tiller substrate and the coating prepared in Example 1.

[0024] Figure 7 The hardness distribution of the coating prepared in Example 1 along the thickness section direction.

[0025] Figure 8 (a) and (b) show the macroscopic morphology of the wear marks on the rotary tiller substrate and the coating prepared in Example 1, respectively.

[0026] Figure 9 (a) and (b) show the three-dimensional morphology of the wear marks on the rotary tiller substrate and the coating prepared in Example 1, respectively.

[0027] Figure 10 Comparison of volumetric wear of rotary tiller substrate and coating prepared in Example 1.

[0028] Figure 11 (a)(b)(c) are microstructure distribution diagrams of the bottom, middle and top sections of the coating prepared in Example 2.

[0029] Figure 12 The image shows the XRD phase analysis of the coating prepared in Example 2.

[0030] Figure 13 The hardness distribution of the coating prepared in Example 2 along the thickness section direction.

[0031] Figure 14 In the middle (a) and (b), respectively, the macroscopic morphology of the wear marks on the rotary tiller substrate and the coating prepared in Example 2 are shown.

[0032] Figure 15In the middle (a) and (b), the three-dimensional morphology of the wear marks on the rotary tiller substrate and the coating prepared in Example 2 are respectively.

[0033] Figure 16 Comparison of volumetric wear of rotary tiller substrate and coating prepared in Example 2. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0035] Example 1

[0036] Samples measuring 60mm × 30mm were cut directly from the blade of the rotary tiller. The substrate was polished with 400-grit sandpaper, and after simple cleaning and drying, it was used for the experiment. The rotary tiller was made of 65Mn material. See [link to rotary tiller and treated sample]. Figure 2 Iron-based powder Fe60 and WC powder were mechanically mixed at a mass ratio of 6:4. An appropriate amount of 5% (v / v) polyvinyl alcohol solution was added as a binder. After mixing thoroughly, the mixture was evenly applied to the surface of a polished and dried rotary tiller sample, with a powder thickness of 1.5 mm. The mixture was then flattened using a pressing plate. Laser cladding was performed using a laser spot size of 4 mm, a laser power of 1200 W, a scanning speed of 7 mm / s, and an overlap rate of 50%. The composition of the iron-based powder Fe60 used in this invention is shown in Table 1. The particle size of the WC powder is 100-150 μm, and the particle size of the iron-based powder Fe60 is 100-200 μm. Figure 3 As shown in (a) and (b).

[0037] Table 1. Elemental composition of Fe60 powder (mass fraction, %)

[0038]

[0039] The cladding coating structure prepared in this embodiment is characterized as follows: After laser cladding, a composite molten coating with a thickness of approximately 1.5 mm was formed on the surface of the rotary tiller blade, as shown below. Figure 4 As shown. From Figure 5 It can be seen that the cladding layer is composed of fine grains from the bottom to the middle and then to the top, with the grains being even finer at the bottom and top. From Figure 6 As can be seen from the data, the rotary tiller matrix (65Mn) is mainly composed of α-Fe, M7C3 (M represents Fe and Cr) and M... 23 Composed of C6. With the addition of WC, the diffraction peaks in the cladding layer pattern increase, see... Figure 6 (b) The composite coating containing 40 wt.% WC mainly consists of α-Fe phase, WC, W2C, M7C3, and M 23Composed of C6. The hard phases in the coating, such as WC and W2C phases, provide excellent dispersion strengthening, resulting in a significant increase in the hardness of the cladding layer. The hardness distribution from the coating surface to the substrate is as follows: Figure 7 As shown, the microhardness of the composite cladding coating near the surface is 1410 HV, which is 4.56 times that of the rotary tiller substrate (309 HV).

[0040] Friction and wear experiments were conducted using an MFT-4000 multifunctional material surface property testing instrument to measure the volumetric wear rate of the substrate and coating samples. A 4mm diameter Si3N4 substrate was selected for the wear pair, with a load of 6N, a wear time of 120 minutes, and a single wear track length of 5mm. The wear track depth is shown in Table 2. The coating significantly reduced the average depth and average width of the wear track. The wear volume is as follows... Figure 10 As shown, the wear volume of the rotary tiller blade substrate is 0.0815 mm. 3 The wear volume of the coating is 0.0135 mm. 3 Its wear volume is 16.56% of the rotary tiller blade base, less than one-sixth.

[0041] Table 2. Abrasion depth of rotary tillers and coatings (WC40%)

[0042]

[0043] Example 2

[0044] Other parameters remain unchanged from Example 1, except that the WC content is adjusted to 30 wt.%. Its overall structure is similar to the coating in Example 1, but the grains are finer, such as... Figure 11 As shown; its phase composition is similar to that of a WC content of 40%, such as... Figure 12 As shown. At this point, the maximum microhardness near the surface of the composite cladding layer can reach 1440 HV, which is 4.67 times that of the rotary tiller steel substrate (309 HV). Under the friction conditions described in the examples, the depth of the wear tracks is shown in Table 3. The coating significantly reduces the average depth and average width of the wear tracks. The wear volume is as follows. Figure 16 As shown, the wear volume of the rotary tiller blade substrate is 0.0815 mm. 3 The wear volume of the coating is 0.0101 mm. 3 Its wear volume is 12.39% of the rotary tiller blade base, less than one-eighth.

[0045] Table 3. Abrasion depth of rotary tillers and coatings (WC30%)

[0046]

[0047] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a high hardness and high wear resistance coating on a rotary blade surface, characterized in that, The method comprises the following steps: (1) cleaning the surface of the rotary blade and drying, the material of the rotary blade being 65Mn; (2) mechanically mixing iron-based powder Fe60 and WC powder in a mass ratio of 7-6:3-4, adding a binder and uniformly stirring, smearing on the surface of the rotary blade and flattening, the particle size of the WC powder being 100-150 µm, the particle size of the iron-based powder Fe60 being 100-200 µm, and the thickness of the powder layer being 1.5 mm; (3) laser cladding the rotary blade workpiece after powder laying, the laser power being 1200 W, the scanning speed being 7 mm / s, and the overlap ratio being 50%.

2. The method for preparing a high-hardness, high-wear-resistant coating on the surface of a rotary tiller blade according to claim 1, characterized in that, The binder in step (2) is a polyvinyl alcohol solution with a volume fraction of 5 %.

3. A rotary blade surface high-hardness and high-wear-resistance coating prepared by the preparation method according to any one of claims 1-2.

4. The high hardness and high wear resistance coating on the rotary blade surface according to claim 3, characterized in that, The microhardness of the coating is greater than 1400 HV.

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